1. Field of the Invention
The invention generally relates to driver and logic circuits utilizing solely NPN-type transistors and, more particularly, to such circuits characterized by low power dissipation and high speed in responding to input signal transitions of either increasing or decreasing sense.
2. DESCRIPTION OF THE PRIOR ART
One technique for providing logic and driver circuits having fast response times and low standby power dissipation uses complementary bipolar transistors. Such circuits are described in copending patent applications Ser. No. 82,254 filed on Oct. 5, 1979 for "Complementary Transistor Inverting Emitter Follower Circuit" in the names of Joseph R. Cavaliere et al and Ser. No. 82,255 filed on Oct. 5, 1979 for "Complementary Transistor Inverting Emitter Follower Circuit" in the names of Richard R. Konian et al. Both of the aforesaid applications make use of an emitter follower series-connected pair of complementary transistors. The former application describes a second pair of complementary transistors, which includes a high performance PNP transistor, for driving the emitter follower transistor pair at high speed. The latter application describes a modified arrangement for driving the emitter follower transistor pair without using any high performance PNP transistor, to eliminate the need for relatively complex and costly high performance PNP technology while retaining most of the high speed and low power dissipation advantages of the circuit disclosed in the former patent application.
It remains desirable, however, that driver and logic integrated circuits, having low standby power dissipation and fast response, be realized using only NPN bipolar transistor technology throughout the entire integrated circuit chip. Preferably the desired circuit should be faster and have a lower speed-power product than prior art, all-NPN, current switch emitter follower circuits which heretofore have been noted for fast response speed in logic applications.